Conventionally, a cross-fin type of heat exchanger is known as a heat exchanger which is used in an air conditioner. This heat exchanger is provided with a plurality of fins which are arranged at prescribed intervals apart, and a plurality of heat transfer tubes which pass through these fins. Air which is sucked into a case of the air conditioner exchanges heat with a refrigerant which flows inside the heat transfer tubes, when the air passes through the gaps between the fins of the heat exchanger. Consequently, the temperature of the air is adjusted. A normal heat exchanger has a row structure in which heat transfer tubes are provided in a plurality of rows along the air flow direction (See, for example, Patent Document 1).
Normally, in an air conditioner, if various paths are formed in such a manner that the flow of refrigerant and the flow of air are orthogonal counter-flows in the heat exchanger (for example, where the refrigerant and air flow in a relationship such as that shown in FIG. 11B), the heat exchange efficiency is higher than in the case of orthogonal parallel flows (for example, where the refrigerant and air flow in a relationship such as that shown in FIG. 11A). More specifically, with orthogonal counter-flows, the flow direction A of the air and the flow direction of the refrigerant in the heat transfer tubes intersect orthogonally or in a near-orthogonal state, while the refrigerant flowing inside a heat transfer tube flows towards a heat transfer tube in a tube row that is positioned to the upstream side of that heat transfer tube, in terms of the air flow direction A. Furthermore, with orthogonal parallel flows, the flow direction A of the air and the flow direction of the refrigerant in the heat transfer tubes intersect orthogonally or in a near-orthogonal state, while the refrigerant flowing inside a heat transfer tube flows towards a heat transfer tube in a tube row that is positioned to the downstream side of that heat transfer tube, in terms of the air flow direction A.
Consequently, if cooling performance is emphasized, for example, respective paths are formed in such a manner that the flow of refrigerant and the flow of air are orthogonal counter-flows in the heat exchanger during a cooling operation. However, in general, in order to improve the APF (Annual Performance Factor), the heating performance is often emphasized, and therefore, in this case, respective paths are formed in such a manner that the flow of refrigerant and the flow of air are orthogonal counter-flows in the heat exchanger during a heating operation.
However, if either the heating performance or the cooling performance is emphasized, then it may become impossible to achieve the other performance sufficiently.
Patent Document 1: Japanese Patent Application Publication No. 2010-78287